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With the increase in global wildfire activity in response to global climate warming, the reconstruction of long-term fire histories and their links to environmental and anthropogenic factors has recently become an important focus of palaeoenvironmental research. Here we compare the precisely radiocarbon (14C) dated long-term histories of vegetation change and fire activity from lakes Ochaul (Cis-Baikal) and Kotokel (Trans-Baikal) in the Lake Baikal Region (LBR) of Siberia, a known source region of wildfires whose past and future relationships with climate, vegetation structure and human economy are still poorly understood. Our results show that under cold and dry glacial climate conditions (32–18.2 ka BP) fire frequencies in both study regions were low. Deglaciation, which was characterised by the spread of woody plants, began around 18.2 ka BP, accompanied by a slight increase in fire activity. Differences in the fire records from both subregions are observed from the end of the Lateglacial (LG), with peak fire activity in Cis-Baikal during the Early Holocene (EH) and in Trans-Baikal during the Middle Holocene (MH). During the Late Holocene (LH) both regions are marked by generally low fire activity. We propose that the long-term spatiotemporal differences in fire activity during the EH–MH interval are primarily driven by vegetation composition and landscape openness and the resulting changes in fire regime. Interestingly, both peaks are also observed in a global-scale fire record, which suggests spatiotemporal complexity of the Holocene fire history. Low charcoal accumulation rates in both records during the Middle Neolithic (ca. 6660–6050 a BP) "cultural hiatus" archaeologically documented for Cis-Baikal suggest an LBR-wide population decline. On the other hand, the spread of Late Bronze and Iron Age cultures into the LBR from 3.5 ka BP may have at least partly driven the increase in fire frequency around Lake Kotokel. • Spatiotemporal complexity in the AMS-dated vegetation and fire records from Siberia. • Increase in fire activity coincides with the onset of deglaciation ca. 18.2 ka BP. • Peak fire activities occur in the Early (Cis-Baikal) and Middle Holocene (Trans-Baikal). • Climate change and vegetation composition controlled glacial-interglacial fire activity. • Holocene fire trends partially correlate with human activities in the Lake Baikal Region. [ABSTRACT FROM AUTHOR]

Paleoclimate change can be quantified by modelling the paleoglacier extents at well-dated moraines. However, previous studies typically use paleo-precipitation changes derived from climate proxies in other locations to constrain paleo-temperature changes. This approach may lead to significant uncertainties due to the lack of a physical basis and spatial-temporal representativeness. To address this issue, we developed a two-step approach to better constrain the paleo-temperature and precipitation changes. The first step is to identify all potential scenarios for temperature-precipitation changes using a coupled glacial-mass-balance and ice-flow model. In the second step, we incorporate a physics-based parameter k , reflecting the sensitivity of precipitation and temperature change, to determine the most probable temperature-precipitation change. We demonstrate our new approach by reconstructing paleoclimate changes of two valley glaciers in the Bhutanese Himalaya (BH). This approach derives a set of temperature reductions of −4.14 °C, −4.08 °C, −0.93 °C, −0.33 ∼ −0.57 °C, and − 0.31 ∼ −0.52 °C, with their corresponding precipitation decreases of 21.4%, 21.0%, 5.2%, 1.7–3.3%, and 1.6–3.0% relative to the present, during the Last Glacial Maximum, Heinrich event 1, Younger Dryas, Neoglacial, and Little Ice Age in BH, respectively. The reconstructed cold and dry climates in BH are consistent with the paleoclimate reconstructions across the Tibetan Plateau, but our approach improved the accuracy of regional paleoclimate reconstructions. These results suggest that temperature change dominates the glacial fluctuations in BH, with additional influences from solar insolation, oceanic and atmospheric circulation changes, and volcanic eruptions. • A new approach to constrain the paleo-temperature and paleo-precipitation changes was proposed. • The reconstructed paleoclimates during the last glacial cycle were colder and dryer than the present. • The collective effect of external and internal variabilities was the potential triggers of glacial fluctuations. [ABSTRACT FROM AUTHOR]

This study examines the isotopic potential of mammoth remains from three paleontological sites in the southeast of the West Siberian Plain (SEWS): Shestakovo, Krasnoyarskaya Kurya, and Volchia Griva. We analysed oxygen isotopes from 29 mammoth enamel and tusk samples and horse and deer enamel samples. We verified sample preservation using ATR-FTIR and obtained δ18Op, δ18Oc, and reconstructed δ18Ow values for 28-22 ka cal BP. Preservation assessments revealed variable preservation conditions. Our findings indicate an increase of 1.4‰ in reconstructed δ18Ow values from glacial levels at 28-23 ka to late-glacial conditions at ca. 17–15.5 ka, likely reflecting climatic warming at the end of the Pleistocene. The extensive fossil material at these sites offers significant potential for further Last Glacial Maximum studies. • We analysed 29 mammoth, deer and horse enamel samples from 3 paleontological sites in Western Siberia. • Preservation of the samples was assessed using ATR-FTIR and oxygen isotope CO3-PO4 equilibrium. • Increase in δ18O values of meteoric waters from 28-23 to 24-22 ka cal BP is attributed to temporal climate development. • Gradient of δ18O depletion between SEWS and Europe suggests similar "continental effects" during the LGM and present day. • SEWS had more pronounced climatic changes than the European plain, transitioning from glacial to lateglacial. [ABSTRACT FROM AUTHOR]

With a rich sequence of floral and faunal remains spanning the past >65,000 years, Boomplaas Cave is among the more important paleoenvironmental archives from South Africa's southern Cape. However, over the last several decades, its paleoenvironmental records have been the subject of conflicting interpretations, fueling uncertainty over fundamental aspects of Quaternary climate change in the region. Most significantly, researchers have variably interpreted the fossil plant and animal assemblages dating to the Last Glacial Maximum (LGM) as indicating harsh and arid or humid and productive conditions. This review critically examines the paleoenvironmental evidence from Boomplaas Cave, focusing on its LGM deposits and how they relate to the contentious problem of moisture availability through time. We show that interpretations of aridity during the LGM either (i) lack robust ecological links between the evidence and the paleoenvironmental interpretation, or (ii) are based on spurious patterns arising from sampling effects. In contrast, interpretations of relatively humid conditions during the LGM are grounded in present-day ecological observations and are consistent with both local and regional paleoenvironmental datasets. Overall, the evidence strongly supports the characterization of the LGM as a time of relatively humid conditions, with the transition to the Holocene characterized by increasing aridity. Several lines of evidence from Boomplaas Cave further suggest that this phase of increased humidity was associated with a dominance of winter rainfall, in contrast to the aseasonal rainfall regime that characterizes the southern Cape today. • Boomplaas Cave is a critical but debated archive of LGM climate in southern Africa. • This study examines its paleo proxies and the interpretations derived from them. • The proxy records indicate greater moisture availability during the LGM. • The proxy records indicate a greater dominance of winter rainfall during the LGM. [ABSTRACT FROM AUTHOR]

Northern Asia (here, the Russian Federation east of the Urals) played a key role in the spread of anatomically modern humans (AMH) across the Eurasian continent during the Upper Palaeolithic (UP). This time interval witnessed the climatically harshest and most variable part of the last glacial epoch when AMH spread to all continents, with the exception of ice-covered Antarctica, thus raising questions about how humans and environments interacted. Our review of available proxy records shows that the study region was largely dominated by productive steppe and tundra plant communities, which promoted a diverse small- to mega-scale fauna throughout the UP. While this rich fauna was an ideal food resource for AMH populations, its possible influence on the growth of woody plants through grazing is less well resolved. Another non-climatic factor that may have impacted on the spread of woody taxa are human activities (e.g. setting fires to facilitate hunting). Evidence that small populations of woody taxa were distributed in climatically favourable habitats comes from plant macroremains from sediment sequences and archaeological sites and from aDNA data. Contrary to the long-standing view of a generally colder-than-present last glacial climate, these proxy records reveal evidence that summers were warmer than today by several degrees Celsius, providing additional advantages for human activities. Another benefit for large herbivores, and thus human subsistence, were the generally low winter precipitation levels (similar to those of the modern steppe regions of Mongolia), which sustained year-round grazing grounds. These factors apparently outweighed the harsh colder-than-present winter conditions and promoted habitation of AMH in Northern Asia even during the Last Glacial Maximum (LGM) ca. 30‒18 cal kyr BP. While our understanding of qualitative climate trends, mainly based on fossil pollen records, has substantially improved, quantification of climate parameters is still a challenging task. For the last glacial interval in Northern Asia, plant macroremains, chironomids, diatoms and ostracods may provide suitable alternative proxies. [ABSTRACT FROM AUTHOR]

The Indian summer monsoon (ISM) is a significant component of global climate and plays a key role in transporting heat and moisture from tropical oceans to the Indian subcontinent. The ISM has a critical role in ecosystem functioning as well as the development of regional agriculture and societies. However, it is difficult to ascertain the extent to which these two drivers interact and impact regional biogeochemistry from contemporary process studies because of the widespread human footprint, and millennial-scale ISM dynamics remain poorly understood over the last 20,000 years. Here we used high-resolution diatoms from alpine lakes at different elevations in the southwest monsoon region to reconstruct summer temperature and environmental variability since the Last Glacial Maximum (LGM). By comparing with other proxy-based temperature reconstructions of the Tibetan Plateau and the monsoon proxy records from South Asia, we found a 3–6 °C warming trend and ISM strengthening since the LGM. Our results indicate that summer temperature began to increase since 17.5 cal. kyr BP, marking the onset of deglacial warming. During the early to middle Holocene, the climate clearly warmed and then decreased afterward. The maximum warm interval occurred during the mid-Holocene, which followed changes in Northern Hemisphere summer insolation. Additionally, examinations of fossil diatom assemblages revealed that changes in compositions were closely linked with global and Indian monsoon climate changes on glacial and interglacial time scales. The abrupt temperature increases from extreme cold to warm transition during the Late-glacial/Holocene boundary (∼3 °C) are strongly associated with regional replacement of major biotic species compositions. The presence of biotic transition and the increased rate of temperature increase during the Late-glacial/Holocene transition confirm the importance of climate change in restructuring biological communities. This suggests that biotic structures necessary to survive such rapid climate regime were susceptible to impacts of the speed and magnitude of temperature change in monsoon region. • Composite mean July temperature inferred by diatoms from multiple lakes and comparison with palaeoclimatic bio-proxies. • Quantitative estimates show a regionally coherent Holocene maximum warmth over the southeastern Tibetan Plateau. • Temperature increases by ca. 1.5–3.4 °C since the Holocene represent a first threshold in ecosystem responses to climate warming [ABSTRACT FROM AUTHOR]

Southern Africa's Greater Cape Floristic Region (GCFR) – a hotspot of biological diversity and palaeo-anthropological evidence for modern human evolution – is a climatically complex region where broad climatic gradients influence the relative importance of plant photosynthetic types in local vegetation. This mix of photosynthetic pathways imprint an isotopic signature on palaeo-records, thereby allowing for the reconstruction of historical climate and vegetation. Here, we use vegetation plot data, coupled with the photosynthetic-type affinities of plant genera, to relate their relative cover to bioclimatic drivers and use these to create spatial distribution models of C 3 and C 4 grasses and CAM shrubs across the contemporary GCFR. We then use palaeodistribution modelling, drawing on downscaled climate models for the Last Glacial Maximum (LGM), to hindcast the LGM distributions of photosynthetic types for the GCFR and its then-exposed offshore areas. In addition, we construct a model to account for the effect of lower atmospheric CO 2 concentration ([CO 2 ]) during the LGM on the competitive interactions between C 3 and C 4 grasses and use this model to hindcast relative C 4 -grass cover across the glacial-era GCFR. Our palaeodistribution models suggest that, even though there were some reductions in CAM cover and shifts in C 3 -/C 4 -dominated grass layers between the LGM and Holocene, these were mostly localised, with changes at the regional scale being relatively muted. For C 3 /C 4 grasses, distributional shifts were even more subtle once sub-ambient glacial [CO 2 ] was accounted for. Our hindcasts of glacial, [CO 2 ]-adjusted grass cover show agreements and inconsistencies with various sedimentary and herbivore-diet records in the palaeo-archive: both lines of evidence suggest the dominance of C 3 species in the strongly winter-rainfall western GCFR; in the eastern GCFR, with muted rainfall seasonality, hindcasts of relative C 3 :C 4 cover and δ13C signals from palaeo-records vary, with greater disparities between them. The lack of significant upheavals in the distribution of photosynthetic types suggests that the GCFR presented a relatively stable and dependable resourcescape for hunter-gatherer populations through the glacial–interglacial cycle of the LGM–Holocene transition. Our maps of relative C 3 -/C 4 -grass and CAM-shrub cover provide a reasonable surrogate for relative biomass of different photosynthetic types in local vegetation at a landscape scale and depict an independent estimate of carbon isoscapes across the GCFR – under both an interglacial (Holocene) and glacial (terminal Pleistocene) climate – against which palaeo-records can be assessed. • Spatial models of relative cover of CAM shrubs and C 3 /C 4 grasses under current and LGM climates • Spatial model of relative C 4 -grass cover under LGM climate and atmospheric CO 2 concentration ([CO 2 ]) • Muted changes in distribution of photosynthetic types through LGM–Holocene transition • Distributional shifts for C 4 grasses more subtle when sub-ambient glacial [CO 2 ] is accounted for • Maps of CAM-shrub and C 3 -/C 4 -grass cover can be used to assess palaeo-records of carbon isoscapes [ABSTRACT FROM AUTHOR]

The present-day ocean ventilation in the Arctic Mediterranean (Nordic Seas and Arctic Ocean), via transformation of northward inflowing warm Atlantic surface water into cold deep water, affects regional climate, atmospheric circulation and carbon storage in the deep ocean. Here we study the glacial evolution of the Arctic Mediterranean circulation and its influence on glacial climate using radiocarbon reservoir-age reconstructions on deep-sea cores from the Fram Strait that cover the late glacial period (33,000–20,000 yr ago; 33–20 ka). Our results show high Benthic-Planktic 14C age differences of ∼1500 14C years 33–26.5 ka suggesting significant water column stratification between ∼100–2600 m water depth, and reduction and/or shoaling of deep-water formation. This phase was followed by break-up of the stratification during the Last Glacial Maximum (LGM; 26–20 ka), with Benthic-Planktic 14C age differences of ∼250 14C years, likely due to enhanced upwelling. These ocean circulation changes potentially contributed to the final intensification phase of glaciation via positive cryosphere-atmosphere-ocean circulation-carbon cycle feedbacks. Our data also do not support 'extreme aging' of >6000 14C years in the deep Arctic Mediterranean, and appear to rule out the proposed outflow of very old Arctic Ocean water to the Nordic Seas during the LGM and to the subpolar North Atlantic Ocean during the deglacial period. • Strong ocean stratification in the Fram Strait during the late glacial (33–26 ka). • Breakup of ocean stratification during the LGM (26–20 ka) due to enhanced upwelling. • No extreme aging of >6000 yr in the Arctic Mediterranean as previously suggested. [ABSTRACT FROM AUTHOR]

• A multi-biomarker record from Lake Elsinore, CA sediment core spans 32–9 ka. • Deglacial warming and storm-track shifts are consistent with prior studies nearby. • Plant wax hydrogen isotopes indicate storm-track changes during the last glacial. • Lipids show temperatures varied during the last glacial, including extreme warmth. Reconstructions of past hydroclimate provide a means to understand precipitation responses to global ocean-atmosphere climate dynamics beyond the scope of that in the instrumental record. Late glacial climate was characterized by abrupt variability in ice and ocean dynamics, however the implications for hydroclimate are not as well known. Here we present organic geochemical proxy evidence for precipitation isotopes based on plant leaf wax hydrogen isotopic compositions (δ D wax) and temperature proxy evidence based upon the branched glycerol dialkyl glycerol tetraethers (brGDGTs), that derive from the membrane lipids of bacteria, each extracted from a sedimentary archive in Lake Elsinore, California spanning 32–9 ka. We add proxy evidence for vegetation and salinity from additional biomarker analyses and compare to prior pollen and sedimentological evidence from the same core. Our record indicates a strong deglacial warming of 10 °C in Lake Elsinore (beginning at 14.5 ka) that accompanied a D-enrichment of precipitation of +90‰ and more C 4 vegetation (12–10 ka), after a cold, wet and C 3 -dominated phase (20–14.5 ka), indicating winter-dominated precipitation during the Last Glacial Maximum and Heinrich Stadial 1. During the late glacial (32–20 ka) we find abrupt variability, with precipitation isotopic shifts (∼70‰) that are independent of temperature swings implicating changes in storm track, rather than local temperature as drivers of the precipitation isotope signal. Temperature is however not irrelevant for hydroclimate: we find extreme warmth at 29.4 ka and 26.8 ka, the latter coincident with existing reports of an extended dry period (27.5–25.5 ka), suggesting a long hot and dry interlude during the generally cooler glacial period. We compare δ D wax with speleothem δ 18 O from Nevada, also within the winter-dominated precipitation region. Our results corroborate the Last Glacial Maximum and deglacial signals, and fill gaps revealing storm-track instability from 32–20 ka, however the pacing and magnitude of the biomarker signals merit cautious interpretation. [ABSTRACT FROM AUTHOR]

Here we summarize the motivation and issues surrounding the responses of ice sheets and sea level to past climate warming as part of the PALeo constraints on SEA level rise (PALSEA) working group. Papers in this special issue of Quaternary Science Reviews focus on the timescale of glaciations during the late Pliocene, the magnitude of ice-sheet fluctuations and volume leading up to and during the last glacial maximum, the timing and persistence of ice-sheet impacts on deglacial and future relative sea-level change, and relative sea-level change during peak interglacial climate. A more dynamic cryosphere is noted under both late Pliocene and last glacial cycle climate conditions, while relative sea-level changes during the last deglaciation appear to correspond closely with individual ice-sheet deglaciation. Lastly, relative sea-level change during peak interglacial conditions may have fluctuated by as much as a meter, although the sources of such variability (Greenland, Antarctica or elsewhere) remain elusive. [ABSTRACT FROM AUTHOR]

Abstract Knowledge of changes in the distribution of C 3 and C 4 plants in relation to climate change is the key to predicting the biosphere's response to future climatic warming. There are significant differences in the spatiotemporal evolution of C 4 plant abundance at different latitudes since the Last Glacial Maximum (LGM), and the factors responsible remain debated. In this study, we reconstructed the spatiotemporal pattern of C 4 plants in China since the LGM, based on a synthesis of δ13C records of soil organic matter from paleosol sequences and δ13C records of individual n-alkanes from lake and marine sediments. The results indicate that, spatially, maximum C 4 abundance during the LGM was in South China; while maximum C 4 abundance occurred in the Chinese Loess Plateau in North China during the early and mid-Holocene. Temporally, in North China, C 4 plant abundance initially increased since the LGM, reached a maximum during the early and mid-Holocene and then decreased; however, the opposite trend occurred in South China. Combined with a physiological-process model used to study the sensitivity of C 3 and C 4 plants to changes in climate and atmospheric p CO 2 in different regions, our results reveal that temperature was the dominant factor driving C 4 plant expansion in North China, whereas atmospheric p CO 2 and precipitation were the main factors controlling C 4 plant abundance in South China. Highlights • Spatiotemporal pattern of C 4 plant abundance across China since the LGM was reconstructed. • Increase in C 4 abundance in mid-latitude China was triggered by increased temperature. • Decrease in C 4 abundance in low-latitude China was a response to increasing atmospheric p CO 2 and precipitation. [ABSTRACT FROM AUTHOR]

Abstract Many studies of Holocene relative sea-level (RSL) changes across Antarctica assume that their reconstructions record uplift from glacial isostatic adjustment caused by the demise of the Last Glacial Maximum (LGM) ice sheets. However, recent analysis of GPS observations suggests that mantle viscosity beneath the Antarctic Peninsula is weaker than previously thought, which would imply that solid Earth motion is not controlled by post-LGM ice-sheet retreat but instead by late Holocene ice-mass changes. If this hypothesis is correct, one might expect to find Holocene RSL records that do not reflect a monotonic decrease in the rate of RSL fall but show variations in the rate of RSL change through the Holocene. We present a new record of late Holocene RSL change from Torgersen Island near Palmer Station in the western Antarctic Peninsula that shows an increase in the rate of relative sea-level fall from 3.0 ± 1.2 mm/yr to 5.1 ± 1.8 mm/yr during the late Holocene. Independent studies of the glacial history of the region provide evidence of ice-sheet changes over similar time scales that may be driving this change. When our RSL records are corrected for sea-surface height changes associated with glacial isostatic adjustment (GIA), the rate of post-0.79 ka land uplift at Torgersen Island, 5.3 ± 1.8 mm/yr, is much higher than the rate of uplift recorded at a nearby GPS site at Palmer Station prior to the Larsen B breakup in 2002 AD (1998-2002 AD; <0.1 mm/yr), but similar to the rates observed after 2002 AD (2002-2013 AD; 6–9 mm/yr). This substantial variation in uplift rates further supports the hypothesis that Holocene RSL rates of change are recording responses to late Holocene and recent changes in local ice loading rather than a post-LGM signal across portions of the Antarctic Peninsula. Thus middle-to-late Holocene RSL data may not be an effective tool for constraining the size of the LGM ice sheet across portions of the Antarctic Peninsula underlain by weaker mantle. In addition, current global-scale GIA models are unable to predict our observed changes in late Holocene RSL. Complexities in Earth structure and neoglacial history need to be taken into consideration in GIA models used for correcting modern satellite-based observations of ice-mass loss. [ABSTRACT FROM AUTHOR]

Abstract Millennial scale events marked by the contribution of detrital sand are recorded in North Atlantic sediments during the Last Glacial Maximum (LGM), between Heinrich events (HE) 1 and 2, and left their imprint on Laurentian Fan (LF – 43°N) sediments off eastern Canada. The LF counterpart of the well-known detrital events consist of glacial red-brick sediments resulting from subglacial flows separated by olive-grey sediments appears at ∼21.4–19.9 and ∼19.5–18.65 cal kyr BP. High-resolution analyses of diatom assemblages and lithic grains coupled with planktonic oxygen isotopic records reveal that while the red sediment is almost barren of diatoms, foraminifera and lithics (>150 μm), they are abundant in the olive-grey sediment. Diatom assemblages reveal three phases during these events: (1) initial relatively warm/temperate conditions followed by (2) very cold surface water and drifting ice, and (3) a final phase characterized by relatively warmer waters and the appearance of detrital carbonate. Although these events possibly reflect the variability specific to the slope water region, they are likely the response to Atlantic Meridional Overturning Circulation perturbations and ice-sheet instability. Through a chain of mechanisms, meltwater inputs into the North Atlantic led ultimately to an increased volume of tropical waters and part of the heat stored in the subsurface was flushed by a brief convective episode that was not sustained, accounting for the return of cold conditions after the events. The sequence of mechanisms deduced from the paleo data here and elsewhere is consistent with previous modeling results. These data suggest that the detrital events between Heinrich event 1 and 2 may be synchronous across the North Atlantic, and that the LGM was probably not a time of prolonged steady state in the climate system. Highlights • Detailed description oceanographic changes of some LGM detrital events. • Diatom records evidence the presence of relatively warmer waters at the beginning and by the end of the events. • Possible links between detrital events, ice-sheets instability and AMOC perturbations. [ABSTRACT FROM AUTHOR]

The last deglacial was marked by tremendous changes in ocean temperature and circulation as well as atmospheric CO 2 and 14 C. We employed the “ 14 C plateau-tuning technique” to a centennial-scale planktic 14 C record of core MD08-3180 retrieved S.W. of the Azores Islands at ∼3060 m water depth to establish both a new standard of absolute age control and a record of past 14 C reservoir ages of ocean surface waters. Both δ 18 O minima of G. bulloides and high planktic reservoir ages of ∼1600 to 2170 yr suggest two major melt water incursions that reached from the Labrador Sea up to the subtropics over Heinrich Stadial 1 (HS-1). In parallel, we established a record of (apparent) benthic ventilation ages that add the planktic 14 C reservoir ages together with the benthic-planktic 14 C age difference at the site and time of deposition, a sum finally adjusted to past changes in atmospheric 14 C that occurred since the time of deep-water formation. Near the Azores apparent deep-water ages of the Last Glacial Maximum were as low as 340–740 yr, which suggests a lateral advection of young North Atlantic Deep Waters (NADW) from subpolar regions south of Iceland, in harmony with recent model simulation and in contrast to a widely assumed major shoaling of glacial deep-water formation. During HS-1, local benthic ventilation ages increased up to 2200–2550 yr, thus suggest an incursion of old southern-source deep waters, an unstable regime that was interrupted by brief pulses of NADW incursion near 16, 15.6 cal. ka, and most salient, near 14.9/14.7 ka. [ABSTRACT FROM AUTHOR]

Abstract The modern southern Mariana Trench is characterized by oligotrophic surface waters, resulting in low primary productivity and well-oxygenated bottom waters. This study investigates changes in the redox conditions of bottom waters in the southern Mariana Trench during the Last Glacial Maximum (LGM) and their potential causes. We measured major, trace, and rare earth elements (REE) in three gravity cores (GC03, GC04, and GC05) and one box core (BC11) retrieved from the southern Challenger Deep at water depths from 5289 to 7118 m. The upper sediment layers of both GC05 and BC11 are dominated by valve fragments of the giant diatom Ethmodiscus rex , forming laminated diatom mats (LDMs). 14C-AMS dates of bulk organic matter show that the LDMs accumulated between 18.4 and 21.8 kyr B.P., corresponding to the LGM. Modest enrichments of U and Mo along with weak or absent Ce anomalies in the LDM point to suboxic conditions during the LGM. In contrast, non-LDM samples exhibit little to no enrichment of redox-sensitive elements as well as negative Ce anomalies, indicating deposition under oxic bottom-water conditions. The Ce anomalies are considered valid proxies for bottom-water redox conditions because REE signatures were acquired in the early diagenetic environment, as indicated by strong P-REE correlations and middle-REE enrichment associated with early diagenetic cycling of Fe-Mn oxyhydroxides in the sediment column followed by capture of the REE signal by biogenic and/or authigenic apatite. We postulate that the more reducing bottom-water conditions during the LGM were linked to increased primary productivity induced by enhanced Asian dust input. As shown in earlier studies, the increased primary productivity associated with Ethmodiscus rex blooms in the eastern Philippine Sea played a significant role in capturing atmospheric CO 2 during the LGM. Consequently, the magnitude of atmospheric CO 2 sequestration by giant diatom blooms during the LGM may have been greater than previously envisaged. Highlights • Elemental and radiocarbon analysis of southern Mariana Trench (SMT) sediments since 30 ka. • Shift to more reducing (suboxic) deep waters during the Last Glacial Maximum (LGM). • Blooms of giant diatom Ethmodiscus rex formed laminated diatom mats (LDMs) during LGM. • Redox changes were due to increased primary productivity induced by enhanced Asian dust inputs. • Biogenic and authigenic apatite are the main carriers of rare earth elements (REEs) in SMT sediments. [ABSTRACT FROM AUTHOR]

Numerous cases of timing differences between glacier advances recorded in mountain environments have been documented over the last decade, usually suggesting potential age conflicts between the different dating techniques. The frequent use of a single technique to date numerically a given glacial sequence makes it difficult to address to what extent age differences can be an artifact related to biased numerical age results or a paleoclimate signature. Here we present a new set of 43 numerical ages based on three dating techniques — 10 Be surface exposure dating; radiocarbon; and optically stimulated luminescence— that complement the chronology of Pleistocene glacial advances in the Porma valley, in the central Cantabrian Mountains of Spain. Results compliment previous chronologies in the area, supporting an important glacial advance during Marine Isotope Stage 3 (Stage IIa: ∼56 ka) that culminated with the Last Glacial Maximum advance (Stage IIb: ∼33–24 ka) of MIS 2 in response to increased rainfall and solar insolation minima. Glacier fronts reached elevations as low as 1130 m a.s.l. possibly without overriding evidence related to the previous Pleistocene glacial maximum extent. Glacier recession in the Cantabrian Mountains started at 21–20 ka ago, after the global LGM. We suggest that the recession was initiated by increased insolation followed by hyper-cool and dry conditions during Heinrich Stadial 1 in response to meltwater discharges in the North Atlantic. [ABSTRACT FROM AUTHOR]

Studies of past glacial cycles yield critical information about climate and sea-level (ice-volume) variability, including the sensitivity of climate to radiative change, and impacts of crustal rebound on sea-level reconstructions for past interglacials. Here we identify significant differences between the last and penultimate glacial maxima (LGM and PGM) in terms of global volume and distribution of land ice, despite similar temperatures and radiative forcing. Our analysis challenges conventional views of relationships between global ice volume, sea level, seawater oxygen isotope values, and deep-sea temperature, and supports the potential presence of large floating Arctic ice shelves during the PGM. The existence of different glacial ‘modes’ calls for focussed research on the complex processes behind ice-age development. We present a glacioisostatic assessment to demonstrate how a different PGM ice-sheet configuration might affect sea-level estimates for the last interglacial. Results suggest that this may alter existing last interglacial sea-level estimates, which often use an LGM-like ice configuration, by several metres (likely upward). [ABSTRACT FROM AUTHOR]

[Display omitted] • Late Pleistocene glacial landforms and paleoclimate in the Eastern Carpathians. • Presented inventory of 214 glacial cirques and 147 palaeo-glaciers in 14 massifs. • LGM ELA mimics the pattern and magnitude of the modern climatic ELA. • ELA and cirque elevation trends show dominant westerlies in Central Europe during LGM. • Crucial role of orographic induced precipitation in dry continental glacial climate. The Eastern Carpathians are the northeasternmost sector of the European Alpine Mountain system and comprise 14 formerly glaciated massifs that stretch over 300 km into the territories of Ukraine and Romania. In this study we provide a regional overview on Late Pleistocene glaciation in the Eastern Carpathians integrating recently published and new geomorphological data which include mapped glacial landforms and glacier reconstruction of the maximal ice extent (MIE) which is assigned to the global Last Glacial Maximum (LGM). Thus we obtain a complete inventory of glaciation in the Eastern Carpathians, including the documentation of 214 glacial cirques and 147 small mountain glaciers with a total area of 153.2 km2. The estimated LGM equilibrium line altitude (ELA) shows a strong rise of 2.4 m/km from the northwest (1270 m asl) to the southeast (1870 m asl), as well as a consistent eastward rise on several W-E transects (2–3.4 m/km). Similar patterns are shown by the palaeoglaciation level and the cirque floor altitude trend, which mimic the pattern of modern temperature-precipitation ELA (tpELA) in the region. Reconstructed palaeoglacial trends reflect dominant W-NW precipitation-wind regime and an enhanced zonal North Atlantic circulation pattern in the far interior of Europe in full glacial climate. This is consistent with both regonal palaeoclimatic simulations and wind regime proxies which indicate that the pattern of LGM circulation was similar to the present circulation, although the magnitude may have increased during glacial conditions. Additionally, based on the wide array of glacial landscapes inventoried in this study, ranging from traces of small niche/cirques to about 7 km long valley glaciers, we propose a quantitative approach to define the distinct stages of glacial landscape development based on the relationship between the Pleistocene ELA and mountain hypsometry. [ABSTRACT FROM AUTHOR]

The timing and extent of late Quaternary glaciation in the Hailuogou valley of eastern Tibetan Plateau have been extensively studied over past decades. Debate however exists in the timing of the Gongga II moraine that represents the maximum glaciation in the Hailuogou valley. Furthermore, the Gongga II glaciation is not quantitatively reconstructed; and what climate conditions could support this maximum glaciation is unknown. This study used a glacier-climate model driven by data from local weather stations to simulate the Gongga II glacier extent by fitting modeled glaciers to field geological evidence. Running multiple simulations with different temperature-precipitation combinations, we inferred the climate scenarios sufficient to generate the Gongga II glacier extent. The modeled Gongga II glaciers have an area of ∼119 km 2 and an average volume of 1.35 × 10 10 m 3 , with an average equilibrium-line altitude of 4050 m asl. Combined with other independent climate reconstructions, the glacier-climate model simulations suggested that the Gongga II glacial stage most likely occurred in the LGM. [ABSTRACT FROM AUTHOR]

Contemporary climate change has resulted in great uncertainty in how glaciers and ice sheets around the Earth might evolve. It has long been appreciated that the contemporary West Antarctic Ice Sheet (WAIS) shares many similarities with the former Barents Sea Ice Sheet (BSIS). Therefore, an increasing number of studies have sought to investigate the Barents Sea glacial record to better understand marine-based glaciation. This paper reports the analysis of a new high-resolution bathymetric survey covering ~ 55,000 km 2 in the central Barents Sea. The relative chronologies of newly-mapped glacial landforms such as mega-scale glacial lineations, grounding-zone wedges, moraines, and crevasse-squeeze ridges are used to reconstruct the ice sheet dynamics in the central Barents Sea. Our results show that the ice sheet responded dynamically with different periods of retreat, advance, and stagnation observed. These new landform records have been integrated with other geomorphological records in order to reconstruct the retreat pattern of the BSIS between 17–14 ka, when the Fennoscandian Ice Sheet is thought to have uncoupled from the BSIS. Our data shows that the dynamic drawdown of the ice sheet saddle by ice streams was probably the primary mechanism in separating the two ice sheets. After the ice sheets uncoupled, the BSIS is shown to have retreated episodically with several periods of relative stability. Geomorphological records such as those from the BSIS can be used to constrain ice sheet modelling and will help to develop a clearer understanding of marine-based glaciation and the role of ice streams in driving ice sheet evolution. [ABSTRACT FROM AUTHOR]

We modelled the European distribution of vegetation types at the Last Glacial Maximum (LGM) using present-day data from Siberia, a region hypothesized to be a modern analogue of European glacial climate. Distribution models were calibrated with current climate using 6274 vegetation-plot records surveyed in Siberia. Out of 22 initially used vegetation types, good or moderately good models in terms of statistical validation and expert-based evaluation were computed for 18 types, which were then projected to European climate at the LGM. The resulting distributions were generally consistent with reconstructions based on pollen records and dynamic vegetation models. Spatial predictions were most reliable for steppe, forest-steppe, taiga, tundra, fens and bogs in eastern and central Europe, which had LGM climate more similar to present-day Siberia. The models for western and southern Europe, regions with a lower degree of climatic analogy, were only reliable for mires and steppe vegetation, respectively. Modelling LGM vegetation types for the wetter and warmer regions of Europe would therefore require gathering calibration data from outside Siberia. Our approach adds value to the reconstruction of vegetation at the LGM, which is limited by scarcity of pollen and macrofossil data, suggesting where specific habitats could have occurred. Despite the uncertainties of climatic extrapolations and the difficulty of validating the projections for vegetation types, the integration of palaeodistribution modelling with other approaches has a great potential for improving our understanding of biodiversity patterns during the LGM. [ABSTRACT FROM AUTHOR]

Precipitation is the most important variable of Indonesian climate, yet there are substantial uncertainties about past and future hydroclimate dynamics over the region. This study explores vegetation and rainfall and associated changes in atmospheric circulation during the past 26,000 years in Wallacea, a biogeographical area in central Indonesia, wedged between the Sunda and Sahul shelves and known for its exceptionally high rainforest biodiversity. We use terrestrial plant biomarkers from sediment cores retrieved from Mandar Bay, off west Sulawesi, to reconstruct changes in Wallacean vegetation and climate since the Last Glacial Maximum (LGM). Enriched leaf wax carbon isotope (δ 13 C wax ) values recorded in Mandar Bay during the LGM, together with other regional vegetation records, document grassland expansion, implying a regionally dry, and possibly more seasonal, glacial climate. Depleted leaf wax deuterium isotope (δD wax ) values in Mandar Bay during the LGM, and low reconstructed precipitation isotope compositions from nearby sites, reveal an intensified Austral-Asian summer monsoon circulation and a southward shift of the mean position of the Intertropical Convergence Zone, likely due to strong southern hemisphere summer insolation and the presence of large northern hemisphere ice sheets. Mandar Bay δ 13 C wax was anti-correlated with δD wax during the LGM and the last deglaciation, but was positively correlated during most of the Holocene, indicating time-varying controls on the isotopic composition of rainfall in this region. The inundation event of the Sunda Shelf and in particular the opening of the Java Sea and Karimata Strait between 9.4 and 11.1 thousand years ago might have provided new moisture sources for regional convection and/or influenced moisture source trajectories, providing the trigger for shifts in atmospheric circulation and the controls on precipitation isotope compositions from the LGM to the Holocene. [ABSTRACT FROM AUTHOR]

This paper is the first analysis of differences between Last Glacial Maximum (LGM) and present climates in southern South America considering the state-of-the-art PMIP3 paleoclimatic models. The study is focused on characteristics of temperature and precipitation over the portion of the continent to the south of 20°S at both sides of the Andes Cordillera. Results demonstrate that model outputs coincide with glacial conditions inferred from the very few paleorecords available in the region. Consequently, these models are a valuable tool for inferring additional conditions in areas where there is a lack of proxy information allowing the reconstruction of the past climate at regional scales. The analyzed PMIP3 models expose an LGM cooling of ∼2-5 °C throughout the year over almost all southern South America but differences are even more pronounced in areas around the southern Andes. Models also suggest that LGM precipitation was substantially lower than present over the portion of southern South America to the east of the Andes inferring reductions of ∼20–30% with respect to present-day values in subtropical areas and ∼40–50% in the southern tip of the continent. [ABSTRACT FROM AUTHOR]

Glacier advances in the southern mid-latitudes during the last glacial cycle ( ca . 110–10 ka) were controlled by changes in temperature and precipitation linked to several important ocean-climate systems. As such, the timing of glacial advance and retreat can yield important insights into the mechanisms of Southern Hemisphere climate change. This is particularly important given that several recent studies have demonstrated significant glacial advances prior to the global Last Glacial Maximum (gLGM) in Patagonia and New Zealand, the cause of which are uncertain. The recent increase in chronological studies in these regions offers the opportunity to compare regional trends in glacial activity. Here, we compile the first consistent 10 Be exposure-dating chronologies for Patagonia and New Zealand to highlight the broad pattern of mid-latitude glacial activity over the last glacial cycle. Our results show that advances or still stands culminated at 26–27 ka, 18–19 ka and 13–14 ka in both Patagonia and New Zealand and were broadly synchronous, but with an offset between regions of up to 900 years that cannot be explained by age calculation or physically plausible erosion differences. Furthermore, there is evidence in both regions for glacial advances culminating from at least 45 ka, during the latter half of Marine Isotope Stage (MIS) 3. Glacial activity prior to the gLGM differed from the large Northern Hemisphere ice sheets, likely due to favourable Southern Hemisphere conditions during late MIS 3: summer insolation reached a minimum, seasonality was reduced, winter duration was increasing, and sea ice had expanded significantly, inducing stratification of the ocean and triggering northward migration of oceanic fronts and the Southern Westerly Winds. Glacial advances in Patagonia and New Zealand during the gLGM were probably primed by underlying orbital parameters. However, the precise timing is likely to have been intrinsically linked to migration of the coupled ocean-atmosphere system, which may account for the small offset between Patagonia and New Zealand due to differences in oceanic frontal migration. During deglaciation, advances or still stands occurred in both regions during the southern Antarctic Cold Reversal ( ca . 14.5–12.9 ka) rather than the northern Younger Dryas ( ca . 12.9–11.7 ka). Our findings suggest that major rearrangements of the Southern Hemisphere climate system occurred at various times during the last glacial cycle, with associated impacts on the position and intensity of the Southern Westerly Winds and oceanic fronts, as well as wind-driven upwelling and degassing of the deep Southern Ocean. Thus, reconstructing the timing of glacial advance/retreat using our compilation is a powerful way to understand the mechanisms of past interhemispheric climate change. [ABSTRACT FROM AUTHOR]

During the last glaciation the Eurasian continent was impacted by the global reorganization of atmospheric circulation caused by North Atlantic events, through changes in moisture storm tracks modulated by orography. Our research explores the linkages between climate evolution in the North Atlantic and in the Alps between 30.6 and 12.5 ka, This period, centered on the Last Glacial Maximum, experienced the most recent phase of maximum global ice volume, corresponding to a millennia-long phase of sea-level lowstand, minima in reconstructed sea surface temperatures and isotopic values from polar ice. We present a high-resolution multiproxy record from Lake Fimon at the southern Alpine foothills, where a larch forest-steppe persisted throughout the coldest spells. We analyse the fine climate structure of the MIS 3–2 transition, of the Alpine Last Glacial Maximum stepped by HS2, and provide an unprecedented fine resolution and accurate 14C dating of the Last Glacial Maximum and the early Alpine Lateglacial. We reconstructed quantitative climate parameters based on sensitive pollen descriptors, and derived co-registered sedimentary proxies for dust flux. Reconstructed series suggest that extreme continental spells in the Alps and cold boreal winters match the timing of Heinrich Stadials 2 and 1, episodes of iceberg discharge and release of rock fragments (Ice Rafted Debris) in the North Atlantic. The initiation of the LGM at 27.3 ka is marked by a 4 °C drop in July temperatures, likely responsible for the onset of glacial build-up in the Southern Alpine piedmont. The first extreme continental spell coincides with the British-Irish-sourced IRD event at 26.2 ka and with glacier retreat in the Southern Alps, persisting in the subsequent HS2. Late Glacial glacier collapse and extreme drought occurred during the first half of the HS1, 17.4–16.2 ka. The comparison of the results obtained at Lake Fimon with other terrestrial Eurasian records and with recalibrated marine chronologies from the North Atlantic suggests in-phase reactions of the British-Irish Ice Sheet and of Alpine glaciers and ecosystems to changes in the Atlantic Meridional Circulation. Asymmetric ecoclimatic effects produced by North Atlantic events at the windward and leeward sides of the Alps confirm a southern provenance of moist air masses throughout the LGM. • We explore the linkages between North Atlantic and Alpine climates between 31 and 12 ka. • Temperature and precipitation reconstructed from pollen proxies in lake deposits. • A Larix forest steppe covered the south-eastern alpine border during the LGM. • Extreme continental spells in the Alps match the timing of Heinrich Stadials. • Southern Siberia hosts the closest modern analogues for LGM Alpine vegetation. [ABSTRACT FROM AUTHOR]

Using simulations performed by all available climate models participating in the latest Paleoclimate Modelling Intercomparison Project (PMIP) phase 3 (PMIP3), we revisited the climate over China and the East Asian monsoon during the last glacial maximum (LGM; 21,000 years ago). Similar to previous results obtained from the PMIP phases 1 and 2 (PMIP1/2) models, all nine models reproduced colder than the pre-industrial annual and seasonal temperatures over China during the LGM and underestimated the annual cooling as evidenced by proxy data. The LGM annual and seasonal precipitation and evaporation over China consistently decreased in the models, whereas the very small LGM change in net precipitation (precipitation minus evaporation) differed among models. The annual net precipitation change during the LGM was broadly consistent with reconstructed moisture conditions over most parts of China, especially over the western Tibetan Plateau where the PMIP1/2 models disagreed with the proxy data. Moreover, the LGM winter monsoon circulation weakened (strengthened) over the East Asian continent in four (one) of five models; the summer monsoon circulation generally weakened in two models, whereas it weakened north and strengthened south of about 30°N over East Asia in three models. The spatial patterns of the LGM change in East Asian winter and summer monsoons in the PMIP3 models differed somewhat from those in the PMIP1/2 simulations. [ABSTRACT FROM AUTHOR]

Excavated since the 1860s, the Arudy basin has yielded a number of rich Magdalenian sites that enable us to address the question of the human reoccupation of the lower Pyrenean valleys at the end of the Last Glacial Maximum. Until the 1990s, it was considered that at Arudy this reoccupation started ca. 16,000 cal BP in the Middle Magdalenian and continued into the Upper Magdalenian until ca. 14,000 cal BP. However, since the mid-2000 s, this picture has been modified through a series of new analyses, excavations (caves of Laa 2 and Tastet), 14 C dates and reassessment of ancient collections. Evidence of human occupation ca. 20,000–19,000 cal BP, although limited, has been identified at Laa 2 and Tastet, consistent with numerous data obtained at Pyrenean scale showing a deglaciation of the north Pyrenean foothills as early as the end of the global LGM. The number of sites with evidence of Magdalenian has increased, showing that human presence in the basin was more intensive than previously thought. The Middle and Upper Magdalenian occupations have been redated to at least 18,000–17,500 cal BP to 15,000–14,500 cal BP, with the transition between the two phases probably occurring ca. 16,600–16,200 cal BP. The faunal records of these sites document an emphasis on horse hunting, which is not common in the northern Pyrenees, but also witness an evolution over time in the range of species hunted. Furthermore, the Pyrenean affinities of the Arudy groups and their relations with neighboring regions, such as Spain and the northern part of the Aquitaine basin, can be addressed through new evidence: in particular lithic and osseous raw materials and specific types of projectile tips. These results significantly change our view of the nature, rhythm and chronology of the Late Glacial settlement in this area. [ABSTRACT FROM AUTHOR]

Previous reconstructions of the British–Irish Ice Sheet (BIIS) envisage ice streaming from the Irish Sea to the Celtic Sea at the Last Glacial Maximum, to a limit on the mid-shelf of the Irish-UK sectors. We present evidence from sediment cores and geophysical profiles that the BIIS extended 150 km farther seaward to reach the continental shelf edge. Three cores recently acquired from the flank of outer Cockburn Bank, a shelf-crossing sediment ridge, terminated in an eroded glacigenic layer including two facies: overconsolidated stratified diamicts; and finely-bedded muddy sand containing micro- and macrofossil species of cold water affinities. We interpret these facies to result from subglacial deformation and glacimarine deposition from turbid meltwater plumes. A date of 24,265 ± 195 cal BP on a chipped but unabraded mollusc valve in the glacimarine sediments indicates withdrawal of a tidewater ice sheet margin from the shelf edge by this time, consistent with evidence from deep-sea cores for ice-rafted debris peaks of Celtic Sea provenance between 25.5 and 23.4 ka BP. Together with terrestrial evidence, this supports rapid (ca 2 ka) purging of the BIIS by an ice stream that advanced from the Irish Sea to the shelf edge and collapsed back during Heinrich event 2. [ABSTRACT FROM AUTHOR]

We here suggest a glacial and climate history of the Taimyr Peninsula and Severnaya Zemlya archipelago in arctic Siberia for the last about 150 000 years (ka). Primarily it is based on results from seven field seasons between 1996 and 2012, to a large extent already published in papers referred to in the text – and on data presented by Russian workers from the 1930s to our days and by German colleagues working there since the 1990s. Although glaciations even up here often started in the local mountains, their culminations in this region invariably seems to have centred on the shallow Kara Sea continental shelf – most likely due to expanding marine ice-shelves grounding there, as a combined effect of thickening ice and eustatically lowered sea-levels. The most extensive glaciation so far identified in this region (named the Taz glaciation) took place during Marine Isotope Stage 6 (MIS 6), i.e. being an equivalent to the late Saale/Illinoian glaciations. It reached c. 400 km southeast of the Kara Sea coast, across and well beyond the Byrranga Mountain range and ended c. 130 ka. It was followed by the MIS 5e (Karginsky/Eemian) interglacial, with an extensive marine transgression to 140 m above present sea level – facilitated by strong isostatic downloading during the preceding glaciation. During the latest (Zyryankan/Weichselian/Wisconsinan) glacial cycle followed a series of major glacial advances. The earliest and most extensive, culminating c. 110–100 ka (MIS 5d–5e), also reached south of the Byrranga mountains and its post-glacial marine limit there was c. 100 m a.s.l. The later glacial phases (around 70–60 ka and 20 ka) terminated at the North Taimyr Ice Marginal Zone (NTZ), along or some distance inland from the present northwest coast of Taimyr. They dammed glacial lakes, which caused the Taimyr River to flow southwards where to-day it flows northwards into the Kara Sea. The c. 20 ka glacial phase, contemporary with the maximum (LGM) glaciation in NW Europe, was this glacial cycle's least extensive one up here – probably an effect of precipitation shadow caused by the major glaciations to the west. From the Kara Sea shelf this advance only reached c. 100 km inland, over some limited parts of NW Taimyr. The Severnaya Zemlya islands were only locally glaciated at this time. The lowlands south of the Byrranga Mountains have been a terrestrial “Mammoth steppe” environment during the last c. 50 ka and periglacial permafrosted sediments here have preserved excellent information on its megafauna and vegetation. The latter, according to new DNA-data, had considerably more (for grazing animals nourishing) flowering plants growing than earlier pollen-based (grass dominated) spectra have suggested. [ABSTRACT FROM AUTHOR]

The hydrological conditions during the Last Glacial Maximum in the Eastern Mediterranean have long been debated. In particular, very little is known about the development of high-altitude glaciers in this region. In the present study, morphological and sedimentological evidence, such as U-shape valleys, glacial cirques, and morainic ridges, are used to identify past glaciers on the western slopes of Mount Lebanon, which is by far the highest topography along the eastern Mediterranean coast (3088 m a.s.l.). The geometry of three paleo-glaciers is reconstructed: one 8-km-long glacial tongue stretching from the highest peak down to an elevation of about 2000 m a.s.l., and two small glacial cirques located at about 2300 m a.s.l. The age of maximum glacier advance is constrained from a 10-m-deep 36Cl depth-profile within the diamicton of one terminal moraine, and yields an early LGM timing (between 25.4 ± 3.1 ka and 31.2 ± 4.5 ka), which agrees with the chronology of the last maximum glacier extension in the Eastern Mediterranean. The three glaciers together form a consistent group, compatible with an Equilibrium Line Altitude (ELA) at 2400 m estimated using the Accumulation Area Ratio method. A degree-day model is further used to infer the temperature and precipitation conditions required to depress the LGM ELA to 2400 m. Our results suggest that the observed glacier extent is compatible with early LGM paleo-temperature records of the area only under the condition of decreased precipitation relative to modern times. These findings thus support an early LGM climate of the Levant region that was drier than today. • First evidence of LGM glaciers in the southeastern Mediterranean (Mount Lebanon; 34.25°N) are provided. • The geometry of three glaciers is reconstructed and constrains the LGM Equilibrium Line Altitude at about 2400 m a.s.l. • Glacial and climate modeling indicates a drier LGM climate than today. [ABSTRACT FROM AUTHOR]

Abstract: This review summarises landform records and published age-estimates (largely based upon tephrochronology) to provide an overview of glacier fluctuations upon the Kamchatka Peninsula during the Holocene and, to a lesser degree, earlier phases of glaciation. The evidence suggests that following deglaciation from the Last Glacial Maximum (LGM), the peninsula experienced numerous phases of small-scale glacial advance. During the Late Glacial, moraine sequences appear to reflect the former presence of extensive glaciers in some parts of the peninsula, though little chronological control is available for deposits of this period. During the Holocene, the earliest and most extensive phase of advance likely occurred sometime prior to c. 6.8ka, when glaciers extended up to 8km beyond their current margins. However, these deposits lack maximum age constrains, and pre-Holocene ages cannot be discounted. Between c. 6.8ka and the onset of ‘Neoglaciation’ c. 4.5ka, there is little evidence of glacial advance upon the peninsula, and this period likely coincides with the Holocene climatic optimum (or ‘hypsithermal’). Since c. 4.5ka, numerous moraines have been deposited, likely reflecting a series of progressively less extensive phases of ice advance during the Late Holocene. The final stage of notable ice advance occurred during the Little Ice Age (LIA), between c. 1350 and 1850 C.E., when reduced summer insolation in the Northern Hemisphere likely coincided with solar activity minima and several strong tropical volcanic eruptions to induce widespread cooling. Following the LIA, glaciers upon the peninsula have generally shown a pattern of retreat, with accelerated mass loss in recent decades. However, a number of prominent climatically and non-climatically controlled glacial advances have also occurred during this period. In general, there is evidence to suggest that millennial scale patterns in the extent and timing of glaciation upon the peninsula (encompassing much of the last glacial period) are governed by the extent of ice sheets in North America. Millennial-to-centennial scale fluctuations of Kamchatkan glaciers (encompassing much of the Holocene) are governed by the location and relative intensity of the Aleutian Low and Siberian High pressure systems. Decadal scale variations in glacier extent and mass balance (particularly since the LIA) are governed by inter-decadal climatic variability over the North Pacific (as reflected by the Pacific Decadal Oscillation), alongside a broader trend of hemispheric warming. [Copyright &y& Elsevier]

Abstract: The dramatic climatic and environmental changes that occurred at the end of the last glaciation led to the formation of landforms (e.g., moraines, fluvial ridges, and alluvial terraces) that strongly characterize the landscape in the alluvial plains facing the Alps. This also occurred with the Tagliamento glacier, which built a large LGM moraine amphitheatre in the piedmont sector of the southeastern Alps and fed fluvioglacial systems in the Friulian plain (NE Italy). The Cormor stream was one of the main glacial outwashes and formed an alluvial megafan during the peak of the LGM. At the decline of the LGM, the active belt narrowed and was subsequently abandoned. Since the Lateglacial the Cormor system has been an intermittent stream with limited activity. This sequence of events led to the preservation of large LGM surfaces, which enables their investigation, along with correlatable moraine ridges. The study of megafan depositional phases allows us to precisely constrain the chronology of glacial withdrawal at the end of the LGM, which is difficult in large sectors of the southern Alps. The geomorphological and geological study of the Cormor megafan was realized through the use of remote sensing, DEM analysis, field survey, stratigraphic boreholes, and radiocarbon dating. During the peak glaciation of the LGM, the Cormor experienced widespread aggradation with gravel deposition up to 15–25km from the megafan apex, while the distal sector was dominated by fine-grained sediments. At the end of the LGM the Cormor stream incised the apical portion of its megafan, funnelling the sedimentary discharge and experiencing a limited aggradation in the distal sector with the formation of a progradational lobe. This deposition buried some swampy areas, sealing peaty and organic-rich clayey horizons with 2–4m of sediments. The top of these layers is radiocarbon dated at 22.0–19.5kacal BP and indirectly constrains the chronology of several recessional moraines that formed within the glacial amphitheatre. After this depositional phase, the Cormor megafan was deactivated because of water and sediment discharge concentration of the Tagliamento catchment in the Tagliamento River. This study demonstrates the possibility to reconstruct the timing of the decline of the Tagliamento moraine amphitheatre by studying the distal portion of the related outwash plain. Moreover, new geochronological dating allows chronological comparison of the glacial withdrawal in the eastern sector of the Southern Alps with the global chronology. The results suggest that we can apply this approach also in the distal part of the other alluvial megafans formed by Alpine glacial outwashes in the central part of the Po plain where radiocarbon chronology is almost lacking. [Copyright &y& Elsevier]

Abstract: Fully understanding the timing and climate of Last Glacial Maximum (LGM) is still lack in the head of the Tashkurgan Valley, northwest Tibetan Plateau (TP). The recent improvements in cosmogenic 10Be exposure dating and glacier modeling present an opportunity to estimate the LGM climatic conditions. In the paper, we investigated the moraines and used the 10Be exposure dating on the moraine boulders to constrain the timing of the LGM, the Kuzigun glacial stage in the head of the Tashkurgan Valley. Then, we used a coupled mass-balance and ice-flow model to quantify the paleoclimate from past glacier extents constrained by mapped and dated Kuzigun glacial moraines in the area. We showed that the glaciers terminated at an elevation of 4100–4200 m asl during the Kuzigun glacial stage and the glacial stage occurred during or slightly before 15–23 ka, corresponding to the timing of the global LGM. The modeled mass balances indicated that present-day equilibrium line altitude (ELA) ranges from 5150 to 5250 m asl, and LGM ELA is between 4550 and 4600 m asl in the area, suggesting an ELA lowering of ∼600 m during the LGM. Model results suggested that the temperature during the LGM in the head of the Tashkurgan Valley is 5–8 °C colder than today, considering a 30–70% reduction in precipitation compared to today. The paleoclimate estimates are generally consistence with previous studies that showed the LGM climate was colder and drier than today on the TP. [Copyright &y& Elsevier]

Although numerous global Last Glacial Maximum (gLGM) dating-based paleoclimatic and paleoglacial reconstructions exist for the Tibetan Plateau, no such study is available for the mountains to the Tibetan Plateaus east. Mount Taibai lies east of the Tibetan Plateau, and is known to have experienced glaciation during the Quaternary. In this study, optically stimulated luminescence (OSL) dating was employed to determine the ages of two lateral moraines in the Eryehai Valley on Mount Taibai. The ages obtained were 22.1 ± 1.7–18.7 ± 1.1 ka and 25.8 ± 1.8–24.3 ± 1.5 ka, constrain the timing of the gLGM glaciation in the study area. Using GlaRe and equilibrium-line altitude (ELA) calculations, these two toolboxes, based on a Geographic Information System (GIS), were used to reconstructed the extent of the study areas paleoglacial surface and the ∆ELA. The glacial coverage and ELA for the gLGM in the Eryehai Valley on Mount Taibai were 0.17 km3 and 3351.5 ± 5 m above sea level (asl), respectively. This gLGM ELA is lower than the modern theoretical ELA (4816.5 m asl) by 1465 ± 5 m. From the sporopollen records of the Zoigê Basin in the northwestern Mount Taibai, the precipitation during the gLGM period was equivalent to 60–80% of the present, combined with this record, ∆ELA-based models of the precipitation–temperature relationship (P-T) and the temperature lapse rate (LR) model at the ELA indicate that this area was 7.0 –9.4 °C colder during the gLGM. Combined with other paleoclimatic proxies, a decrease in temperature emerges as the primary driver of glaciation during the gLGM on Mount Taibai. Paleoclimatic reconstructions of paleoglaciers on the Tibetan Plateau and its adjacent mountains also indicate that a drop in temperatures was the principal driver of glacial advances in these regions during the gLGM. Regions affected by the East Asian Monsoon, the Indian Monsoon and the Westerlies would have experienced a greater cooling during the gLGM, while regions blocked by high mountains, and therefore less affected by monsoons and westerly winds, would have seen less cooling. • Optically stimulated luminescence ages constrain the timing of the glaciation in Mount Taibai. • Glacier models are used to interpret the global Last Glacial Maximum climate. • The primary driver of glaciation is a decrease in temperature. • GLGM climate was 7.0–9.4 °C colder than today with precipitation being 60–80% of today. • The temperature decreased differently during the gLGM on the Tibetan Plateau and its adjacent mountains. [ABSTRACT FROM AUTHOR]

Abstract: A 425cm core has been collected from the Gantang subalpine peat bog, in Pingnan County, Fujian Province of Southern China. High-resolution pollen analysis of the core has allowed for the reconstruction of past vegetation and climate changes over the last 50,000years. Today, Fujian province is located in the eastern part of middle subtropical zone where the dominant vegetation is evergreen broadleaved forest that receives its precipitation from the East Asian Monsoon. The pollen record testifies that the vegetation in Fujian varied between subtropical evergreen and warm temperate deciduous forests during the last glacial-interglacial cycle. It appears that during Marine Oxygen Isotope Stage 3, this area was covered with broadleaved forest suggesting warm and wet subtropical condition, whereas the flora was quite different with many ancient elements. The Last Glacial Maximum is distinguished by an increase in warm temperate deciduous taxa, particularly Fagus and Alnus accompanied by abundant Ericaceae, implying a spatial shift of zonal vegetation during this coldest episode in the world. Local swamp developed soon after the Younger Dryas event coinciding with the formation of peatlands in the Northern Hemisphere possibly linked with atmospheric carbon accumulation. A rapid increase in evergreen broadleaved taxa that dominated the local forest occurred at ~ca. 8.2calka BP, indicating the inception of the regional thermal maximum during the Holocene, which was generally characterised by more humid conditions. The middle to late Holocene sees a progressive decline in arboreal elements, and an increase in grasses and Ericaceae. These changes beginning from around 4kacal BP were concordant with the general weakening of the East Asian Monsoon during the Holocene, corresponding with an orbitally induced reduction of boreal summer insolation. This is the first terrestrial high-resolution record from eastern part of middle subtropical areas that evaluates the forest changes through the last glacial-interglacial cycle. [Copyright &y& Elsevier]

Abstract: Pinar Valley is located on the north side of Galana Peak (40° 15′ 21″ N; 5° 18′ 00″ W; 2564m a.s.l.), Sierra de Gredos, in the center of the Iberian Peninsula. Surface exposure ages based on the in situ accumulation of 36Cl were obtained from six moraine boulders and from three bedrock outcrops to investigate the timing of both the last local glacial maximum and the deglaciation. The oldest moraines, which probably overrode older glacial deposits, are coeval to the global Last Glacial Maximum. Subsequently the Pinar glacier underwent minor pulsations close to its maximum position, followed by general glacier retreat after ~17–16ka. Small cirque glaciers probably remained during the terminal Pleistocene but they had completely disappeared by 10ka. [Copyright &y& Elsevier]

Abstract: The pollen, charcoal and sedimentological record from the Maundi crater, located at 2780 m elevation on the south-eastern slope of Mt Kilimanjaro, is one of the longest terrestrial records in equatorial East Africa, giving an interesting insight into the vegetation and climate dynamics back to the early last Glacial period. Our sediment record has a reliable chronology until 42 ka BP. An extrapolation of the age-depth model, as well as matching with other palaeo-records from tropical East Africa, suggest a total age of about 90 ka BP at the bottom of the record. During the last Glacial the distribution as well as the composition of the vegetation belts classified as colline savanna, submontane woodland, montane forest, ericaceous belt, and alpine vegetation changed. The early last Glacial is characterized by high amounts of Poaceae and Asteraceae pollen suggesting a climatically dry but stable phase. Based on the absence of pollen grains in samples deposited around 70 ka BP, we assume the occurrence of distinct drought periods. During the pre-LGM (Last Glacial Maximum) a higher taxa diversity of the ericaceous and montane zone is recorded and suggests a spread of forest and shrub vegetation, thus indicating a more humid period. The taxa diversity increases steadily during the recorded time span. The decent of vegetation zones indicate dry and cold conditions during the LGM and seem to have been detrimental for many taxa, especially those of the forest vegetation; however, the early last Glacial seems to have been markedly drier than the LGM. The reappearance of most of the taxa (most importantly Alchemilla, Araliaceae, Dodonea, Hagenia, Ilex, Myrsine, Moraceae, Piperaceae) during the deglacial and Holocene period suggest a shift into humid conditions. An increase in ferns and the decrease in grasses during the Holocene also indicate increasing humidity. Fire played an important role in controlling the development and elevation of the ericaceous zone and the tree line. During the Holocene no increased anthropogenic impact around the Maundi crater can be observed, since neither higher fire activity nor a spread of hemerophilic plants is recorded. This pollen archive reveals shifts in the upper vegetation zones (ericaceous zone and montane forest zone) of at least 1100 m but underlines the role of Mt Kilimanjaro as a glacial refuge for montane forest species similar to that of the Eastern Arc Mountains. [Copyright &y& Elsevier]

Abstract: Glacial–interglacial climate cycles are known to have triggered migrations and reassortments of tropical biota. Although long-term precessionally-driven changes in temperature and precipitation have been demonstrated using tropical sediment records, responses to abrupt climate changes, e.g. the cooling of Heinrich stadials or warmings of the deglaciation, are poorly documented. The best predictions of future forest responses to ongoing warming will rely on evaluating the influences of both abrupt and long-term climate changes on past ecosystems. A sedimentary sequence recovered from Lake Petén-Itzá, Guatemalan lowlands, provided a natural archive of environmental history. Pollen and charcoal analyses were used to reconstruct the vegetation and climate history of the area during the last 86,000 years. We found that vegetation composition and air temperature were strongly influenced by millennial-scale changes in the North Atlantic Ocean. Whereas Greenland warm interstadials were associated with warm and relatively wet conditions in the Central American lowlands, cold Greenland stadials, especially those associated with Heinrich events, caused extremely dry and cold conditions. Even though the vegetation seemed to have been highly resilient, plant associations without modern analogs emerged mostly following sharp climate pulses of either warmth or cold, and were paralleled by exceptionally high rates of ecological change. Although pulses of temperature change are evident in this 86,000-year record none matched the rates projected for the 21st Century. According to our findings, the ongoing rapid warming will cause no-modern-analog communities, which given the improbability of returning to lower-than-modern CO2 levels, anthropogenic barriers to migration, and increased anthropogenic fires, will pose immense threats to the biodiversity of the region. [Copyright &y& Elsevier]

Abstract: Regional weathering intensity must have changed dramatically at high latitudes during the Quaternary as a consequence of repeated continental glaciation. Investigation of these glacial/interglacial changes at high temporal resolution is possible with the recent development of Pb isotopes in FeMn oxyhydroxide phases as a proxy for region-specific weathering intensity, where increases in the radiogenic component are thought to correspond to increased continental weathering fluxes. Here we present a Pb isotope record sourced from the FeMn oxyhydroxide fraction in marine sediments from IODP Sites U1302/3 on Orphan Knoll (∼3500 mbsl, NW Atlantic), spanning the last 37 ka. Located at the eastern edge of the Laurentide Ice Sheet (LIS), Site U1302/3 is well-placed to monitor changes in weathering intensity associated with LIS glacial history. Overall, the data show a close correspondence to local surface water δ18O, with least radiogenic values during times of heavy δ18O (glacial maximum) and most radiogenic values during times of light δ18O (Holocene). This supports the prediction that weathering intensity in glaciated regions of the North Atlantic correlates with the exposure age of glacial debris. Superimposed on these background trends are extreme radiogenic excursions (e.g. variation in 206Pb/204Pb from ∼19.2–21.0) contemporaneous with Heinrich events and the Younger Dryas. These data are substantially more radiogenic than existing records from the NW Atlantic, and most likely represent episodes of exceptionally high inputs of pre-formed FeMn oxyhydroxides during drainage of the LIS. Due to its extreme isotope composition, at least in the NW Atlantic region, Pb would appear to be a good proxy for the fluxes of weathered continental material and perhaps, by inference, nutrients to the surface ocean. [Copyright &y& Elsevier]

Abstract: We estimated sea surface temperatures (SSTs) in the western Okhotsk Sea during the last glacial maximum (LGM) and the last glacial termination from measurements of the alkenone unsaturation index (UK′ 37), the Tetra Ether indeX of tetraethers consisting of 86 carbon atoms (TEX86), and TEX86 L in piston core sediments, which reveal the climate response of this region to different types of forcings. TEX86 L is a modification of TEX86 proposed for high-latitude ocean regions. The TEX86 L-derived temperatures were not different from the alkenone-derived temperatures from the same and nearby sediment samples. During the LGM, alkenone-derived temperatures in the Okhotsk Sea were relatively warm. These and similarly warm alkenone-derived temperatures found at many other sites in the western North Pacific may reflect a shift in the season of biomarker production from early summer and autumn to mid-summer during the LGM as a result of the expansion of the season of sea-ice cover. Empirical orthogonal function (EOF) analysis of alkenone-derived temperatures at 14 sites from the North Pacific suggested substantial cooling between 20 and 14calkyrBP during the deglaciation at 11 of the sites (including 4 sites in the Okhotsk Sea). This dominant EOF mode suggests either an overall seasonal bias in alkenone-derived temperatures or potential shifts in the Haptophyseae production season. The second EOF mode of variability indicated a deglacial warming trend punctuated by millennial-scale cold events, associated with reorganizations of the Atlantic Meridional Overturning Circulation. The SST pattern corresponding to this EOF mode is indicative of millennial-scale meridional shifts of the axis of the westerly jet, which may have affected heat transport across the Kuroshio. Reconstructed temperature changes, in particular in the Okhotsk Sea, provide insight into the conditions that modulated the ventilation history of intermediate waters in the North Pacific. [Copyright &y& Elsevier]

Abstract: We present a new reconstruction of the Antarctic Ice Sheets between 20 ka BP and the present day. Our reconstruction is derived using a numerical model to generate a physically-consistent ice surface across the whole of the continent. We define the extent of the ice sheet at five time slices; 20, 15, 10, 5 and 0 ka BP, assuming an equilibrium state for the 20 ka BP time slice, and a transient state for the deglacial time slices. The evolution of the ice sheet within the numerical model is driven by variations in temperature, accumulation rate, and relative sea level. In order to reconstruct the concave profile of the ice sheet in marine-grounded regions, such as the Ross and Weddell Seas, we force our model to develop channels of faster flow by defining greater basal sliding along the trajectory of former ice streams. We find a strong dependence upon the basal sliding parameters, and also the position of the grounding line. We use an extensive data base of geological and glaciological data to constrain our ice-sheet reconstruction. Grounding-line extent is prescribed from marine geological data and we test ice-sheet thickness against onshore geological data at 62 sites. Of the five time slices considered, our 20 ka BP reconstruction is the best constrained by data and has an RMS misfit of 147.6 m when compared to observations of ice thickness change between 20 ka BP and the present day. Across all time slices there are large regions of the ice-sheet which are poorly constrained, especially after 20 ka BP. We estimate the spatial distribution of uncertainty in our ice-sheet reconstruction, and note that the solutions are least reliable in regions of complex topography. We predict that the Antarctic Ice Sheets contributed 9 ± 1.5 m of eustatic sea level to the global ocean between 20 ka BP and the present, and our reconstruction with minimum misfit contributes ∼8 m eustatic sea level during this period. These values, which we argue are an upper bound, are lower than many previous estimates. The reconstructed pattern of ice unloading can serve as a new input for glacial isostatic models. [Copyright &y& Elsevier]

Abstract: The Antarctic Peninsula region is currently undergoing rapid environmental change, resulting in the thinning, acceleration and recession of glaciers and the sequential collapse of ice shelves. It is important to view these changes in the context of long-term palaeoenvironmental complexity and to understand the key processes controlling ice sheet growth and recession. In addition, numerical ice sheet models require detailed geological data for tuning and testing. Therefore, this paper systematically and holistically reviews published geological evidence for Antarctic Peninsula Ice Sheet variability for each key locality throughout the Cenozoic, and brings together the prevailing consensus of the extent, character and behaviour of the glaciations of the Antarctic Peninsula region. Major contributions include a downloadable database of 186 terrestrial and marine calibrated dates; an original reconstruction of the LGM ice sheet; and a new series of isochrones detailing ice sheet retreat following the LGM. Glaciation of Antarctica was initiated around the Eocene/Oligocene transition in East Antarctica. Palaeogene records of Antarctic Peninsula glaciation are primarily restricted to King George Island, where glacigenic sediments provide a record of early East Antarctic glaciations, but with modification of far-travelled erratics by local South Shetland Island ice caps. Evidence for Neogene glaciation is derived primarily from King George Island and James Ross Island, where glaciovolcanic strata indicate that ice thicknesses reached 500–850 m during glacials. This suggests that the Antarctic Peninsula Ice Sheet draped, rather than drowned, the topography. Marine geophysical investigations indicate multiple ice sheet advances during this time. Seismic profiling of continental shelf-slope deposits indicates up to ten large advances of the Antarctic Peninsula Ice Sheet during the Early Pleistocene, when the ice sheet was dominated by 40 kyr cycles. Glacials became more pronounced, reaching the continental shelf edge, and of longer duration during the Middle Pleistocene. During the Late Pleistocene, repeated glacials reached the shelf edge, but ice shelves inhibited iceberg rafting. The Last Glacial Maximum (LGM) occurred at 18 ka BP, after which transitional glaciomarine sediments on the continental shelf indicate ice-sheet retreat. The continental shelf contains large bathymetric troughs, which were repeatedly occupied by large ice streams during Pleistocene glaciations. Retreat after the LGM was episodic in the Weddell Sea, with multiple readvances and changes in ice-flow direction, but rapid in the Bellingshausen Sea. The late Holocene Epoch was characterised by repeated fluctuations in palaeoenvironmental conditions, with associated glacial readvances. However, this has been subsumed by rapid warming and ice-shelf collapse during the twentieth century. [Copyright &y& Elsevier]

Abstract: Using the results of 25 climate models under the framework of the Paleoclimate Modelling Intercomparison Project (PMIP) and available proxy data, this study examines the regional climate of China during the Last Glacial Maximum (LGM: 21,000years ago). Compared to the baseline climate, results show that annual surface temperature decreased by 2.00°–7.00°C in China during that period, with an average of 4.46°C, for the ensemble mean of all models. Annual precipitation and evaporation during the LGM were 5–40% less than the baseline values, with an average reduction of 20% (0.60mm/day) and a reduction of 21% (0.41mm/day) at the national scale, based on results from 15 out of the 25 models. These models were selected for their ability to simulate the modern precipitation climatology and for the availability of suitable evaporation data. Both the geographical distribution and magnitude of changes in surface temperature, precipitation, and evaporation during the LGM varied with the seasons and with the models, particularly at the sub-regional scale. Model-data comparisons revealed that the 25 models successfully reproduced the surface cooling trend during the LGM, but they failed to reproduce its magnitude in all four regions of comparison, particularly in the Hexi Corridor and in North and Northeast China. The simulations with computed sea surface temperatures (SSTs) were in better agreement with proxy estimates of surface temperature than those with prescribed SSTs. On the other hand, large-scale LGM-minus-baseline anomalies in annual precipitation minus evaporation agreed well, in a qualitative manner, with lake status-based reconstructions of changes in annual water budgets in East China and the region of 35°–42°N, 74°–97°E. On the eastern Qinghai–Tibetan Plateau, drier climates from the 15 models agreed with pollen-based reconstructions. For most parts of West China excluding the Qinghai–Tibetan Plateau, the simulations with computed (prescribed) SSTs are consistent (inconsistent) with reconstructed moister conditions. [Copyright &y& Elsevier]

Abstract: In arid and semi-arid areas such as southern Africa, rock hyrax (Procavia capensis) middens represent an exceptionally valuable source of late Quaternary palaeoenvironmental information. Pollen and stable isotope data derived from two rock hyrax middens extracted from De Rif in the Cederberg Mountains of the southwestern Cape, casts new light on climatic changes that occurred across the Last Glacial–Interglacial Transition (LGIT) and the Holocene (19.5–0.7calkBP) and how the region''s vegetation responded to these changes. Significant changes in vegetation community composition would be expected in response to environmental changes characteristic of the contrast between ‘glacial’ and ‘interglacial’ climates. However, the pollen assemblages in general indicate that mountain fynbos remained dominant throughout the record and that most of the pollen taxa exhibited only muted frequency variations. This finding could be considered to be inconsistent with indications of marked climatic variations recorded in the stable isotope records for the same midden. An analysis of the geological setting and the bioclimatic affinities of the taxa suggest that the explanation for this inconsistency may lie in the dominating influence of sandstone substrates and the relative resilience of mountain fynbos vegetation to climate change. [Copyright &y& Elsevier]

Abstract: We present a new record from the Última Esperanza region (51°25’-52°25''S), southwestern Patagonia, to unravel the timing and structure of glacial fluctuations during the Last Glacial Termination (T1). This sector of southern South America represents the only windward-facing continental landmass in the Southern Hemisphere that intersects the core of the Southern Westerly Wind belt. Geomorphic, stratigraphic and geochronological evidence indicate the following stages during and since the Last Glacial Maximum (LGM): (i) deposition of prominent moraine complexes during at least two advances dated between ~39 and >17.5ka; (ii) development of an ice-dammed proglacial lake (glacial lake Puerto Consuelo) accompanying ice recession; (iii) active deposition of moraine complexes at intermediate positions followed by recession at ≥15.2ka; (iv) lake level drop and subsequent stabilization between 15.2-12.8ka; (v) a glacial readvance in glacial lake Puerto Consuelo between 14.8-12.8ka; (vi) ice recession, stabilization, and lake level lowering between 12.8-10.3ka; and (vii) glacial withdrawal and disappearance of glacial lake Puerto Consuelo prior to 10.3ka. By comparing our results with the chronologies from neighboring regions we explore whether there was a consistent temporal/geographic pattern of glacial fluctuations during the LGM and T1, and examine their implications at regional, hemispheric, and global scales. The correspondence of these variations with key paleoclimate events recorded in the Southern and the Northern Hemispheres suggest a common forcing that, most likely, propagated through the atmosphere. Regional heterogeneities at millennial timescales probably reflect the influence of processes related to deep ocean circulation, and changes in the position/intensity of the Antarctic Polar Front and Southern Westerly Winds. [Copyright &y& Elsevier]

Abstract: Marine-geophysical and geological data from the seafloor surrounding Kong Karls Land in eastern Svalbard are used to reconstruct Late Weichselian full-glacial flow dynamics and retreat history of the Barents Sea Ice Sheet (BSIS). Grounded ice extended over the entire area during the Last Glacial Maximum (LGM) and produced streamlined sedimentary landforms in the broad bathymetric troughs that flank the Kong Karls Land archipelago. The landforms were produced in subglacial till as a result of subglacial processes at the base of the ice sheet. Drumlins and hill–hole pairs confirm that regional ice-flow was towards the east–northeast through the troughs. Based on the absence of ice-margin recessional features, deglaciation in Olga Strait, Erik Eriksen Strait and the unnamed deep northeast of Kong Karls Land appears to have been rapid in the deeper, outer parts of the troughs. In contrast, in the shallower parts of the troughs, ice recession was slower and minor readvances/still-stands of the ice margin resulted in the formation of recessional moraines. During deglaciation, temporary calving bays formed in the deeper parts of the troughs and calved icebergs were evacuated away from the ice margin through the troughs. Grounding-zone features formed in Olga Strait indicate that retreat here was gradual and punctuated by longer still-stands. The transition from a grounded ice sheet to ice-proximal settings is marked locally by a laminated mud sequence deposited from meltwater plumes from a nearby ice margin. The presence of meltwater-derived facies suggests that melting may have also been a significant ice loss mechanism during retreat. In a broader context, this study is one of the first investigations of the seafloor east of Svalbard, providing evidence that ice drained towards the east-northeast during full-glacial conditions. Ice from this part of the BSIS was an important contributor to the palaeo-ice stream in the large Franz Victoria Trough during the LGM. [Copyright &y& Elsevier]

Abstract: Shell weights of Globigerinoides sacculifer and the elemental concentration of magnesium and calcium (Mg/Ca) from Globigerinoides ruber measured from an Arabian Sea sediment core, AAS9/21, exhibit an inverse relationship with each other, which reveals that shell weights are mainly controlled by surface water [CO3 =] rather than calcification temperature. Down core shell weight variations of Core AAS9/21 show an excellent correspondence with CO2 concentrations in an Antarctic Ice Core, which reveals that planktic forminifera shells can trace atmospheric CO2 due to the resultant change in surface water [CO3 =]. Hence, shell weights of G. sacculifer can be used as a proxy to reconstruct atmospheric CO2 concentrations in the past. Here, based on the shell weights, surface water [CO3 =] change in the Arabian Sea is quantified and found that a [CO3 =] variation of ∼8μmol/kg occurred during the Holocene and a ∼36μmol/kg variation occurred during the last glacial period. [ABSTRACT FROM AUTHOR]

Abstract: Stratigraphic interpretations and infrared stimulated luminescence (IRSL) ages document the glacial history of the Middle Rakaia Gorge section of the Rakaia Valley, Canterbury, New Zealand, during the last two glacial cycles. Sheets of glaciolacustrine sediments several tens of metres in thickness can be traced at least 10 km upstream of the Rakaia Gorge. The stratigraphic package is capped by outwash gravels associated with the last glacial maximum (LGM) advances. The dominant inferred sedimentary environments in the sequence are 1) pro-glacial and paraglacial lake beds, 2) sub-aqueous ice-contact fans, 3) sub-aqueous mass flow deposits 4) supraglacial dump material and 5) outwash gravels. Syndepositional deformation, associated with glacitectonic deformation, is common. The stratigraphy records glacier margin oscillations, including six significant advances. These occurred in early MIS 6, mid-MIS 6, MIS 5b (c100–90 ka), MIS 5a/4 (c 80 ka), mid-MIS 3 (c 48 ka), and late MIS 3 (c 40ka). All the post-MIS 6 advances can be corroborated from other sites in New Zealand and the timings appear to coincide with both Southern Hemisphere insolation minima and maxima, suggesting variable combinations of climatic forcing in New Zealand glaciation. [ABSTRACT FROM AUTHOR]

Abstract: The last glacial maximum (LGM) outline and subsequent retreat pattern (21–7kyr) of North American ice sheets are reasonably well established. However, the evolution of the ice sheets during their build-up phase towards the LGM between 115 and 21kyr has remained elusive, making it difficult to verify numerical ice sheet models for this important time interval. In this paper we outline the pre-LGM ice sheet evolution of the Laurentide and Cordilleran ice sheets by using glacial geological and geomorphological records to make a first-order reconstruction of ice sheet extent and flow pattern. We mapped the entire area covered by the Laurentide and Cordilleran ice sheets in Landsat MSS images and approximately 40% of this area in higher resolution Landsat ETM+ images. Mapping in aerial photographs added further detail primarily in Quebec-Labrador, the Cordilleran region, and on Baffin Island. Our analysis includes the recognition of approximately 500 relative-age relationships from crosscutting lineations. Together with previously published striae and till fabric data, these are used as the basis for relative-age assignments of regional flow patterns. For the reconstruction of the most probable ice sheet evolution sequence we employ a stepwise inversion scheme with a clearly defined strategy for delineating coherent landforms swarms (reflecting flow direction and configuration), and linking these to previously published constraints on relative and absolute chronology. Our results reveal that ice-dispersal centres in Keewatin and Quebec were dynamically independent for most of pre-LGM time and that a massive Quebec dispersal centre, rivalling the LGM in extent, existed at times when the SW sector of the ice sheet had not yet developed. The oldest flow system in eastern Quebec-Labrador (Atlantic swarm had an ice divide closer to the Labrador coast than later configurations). A northern Keewatin-Central Arctic Ice Sheet existed prior to the LGM, but is poorly chronologically constrained. There is also evidence for older and more easterly Cordilleran Ice Sheet divide locations than those that prevailed during the Late Wisconsinan. In terms of ice sheet build-up dynamics, it appears that “residual” ice caps after warming phases may have played an important role. In particular, the location and size of remnant ice masses at the end of major interstadials, i.e. OIS 5c and 5a, must have been critical for subsequent build-up patterns, because such remnant “uplands” may have fostered much more rapid ice sheet growth than what would have occurred on a fully deglaciated terrain. The ice-sheet configuration during stadials would also be governed largely by the additional topography that such “residual” ice constitutes because of inherent mass balance–topography feedbacks. [Copyright &y& Elsevier]

Abstract: While the abrupt climate events of the last deglaciation are well defined in ice core records from the polar regions of both hemispheres, their manifestation elsewhere is less well constrained. Here we compile 104 high-resolution paleoclimate records to characterize the timing and spatial pattern of climate change during the last deglaciation. This compilation indicates relatively concurrent timing of the Last Glacial Maximum (LGM; peak glacial conditions) and the Altithermal (peak interglacial conditions) in the Northern (22.1±4.3ka and 8.0±3.2ka) and Southern (22.3±3.6ka and 7.4±3.7ka) Hemispheres, suggesting the hemispheres were synchronized by greenhouse gases, local insolation, and/or Northern Hemisphere induced ocean circulation changes. The magnitude of the glacial–interglacial temperature change increases with latitude, reflecting the polar amplification of climate change, with a likely minimum global mean cooling of ∼−4.9°C during the LGM relative to the Altithermal. Empirical orthogonal function (EOF) analysis of 71 records spanning 19–11ka indicates that two modes explain 72% of deglacial climate variability. EOF1 (61% of variance) shows a globally near-uniform pattern, with its principal component (PC1) strongly correlated with changes in atmospheric CO2. EOF2 (11% of variance) exhibits a bipolar seesaw pattern between the hemispheres, with its principal component (PC2) resembling changes in Atlantic meridional overturning circulation strength. EOF analysis of 90 records from 15 to 11ka indicates that northern and southern modes of climate variability characterize the Younger Dryas-Bølling/Allerød interval. These modes dominate at the higher latitudes of each hemisphere and exhibit a complex interaction in the tropics. The magnitude of the Younger Dryas climate anomaly (cooler/drier) increases with latitude in the Northern Hemisphere, with an opposite pattern (warmer/wetter) in the Southern Hemisphere reflecting a general bipolar seesaw climate response. Global mean temperature decreased by ∼0.6°C during the Younger Dryas. Therefore, our analysis supports the paradigm that while the Younger Dryas was a period of global climate change, it was not a major global cooling event but rather a manifestation of the bipolar seesaw driven by a reduction in Atlantic meridional overturning circulation strength. [Copyright &y& Elsevier]